1. Field of the Invention
The present invention relates generally to memory devices. More particularly, the present invention relates to a zero power standby mode in a memory device, and even more particularly, to a zero power standby mode in a system, such as a wireless battery powered handheld device.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Wireless, battery-powered handheld devices, such as cellular phones, handheld computers, and personal digital assistants (PDAs) are becoming increasingly useful in today's computer industry. Cellular phones are becoming increasingly tantamount to competent business practices, in addition to being highly demanded for personal use. Conventional PDA units and handheld computers typically provide a user with a handheld device which serves as an abbreviated version of a larger laptop or desktop computer system. They provide a user with an operating system and various software programs to accommodate scheduling, word processing, and a variety of other functions. Advantageously, these units comprise small, light-weight systems which provide a significant amount of computing power. However, it is clear that with the advantages of decreasing the size of a computing system, certain functional tradeoffs typically must be made.
With the proliferation of wireless, battery-powered handheld devices, one of the biggest challenges for designers is to provide a wireless power supply which is small enough to be incorporated into these small and mobile devices, while providing a sufficient amount of power to provide adequate functionality of the device for as long as possible. Techniques for reducing power consumption without reducing device functionality, such as by providing low standby power while the device is not being used, are becoming increasingly important to extended battery usage. For handheld devices incorporating memory chips such as Static or Dynamic Random Access Devices or FLASH (SRAMs or DRAMs or FLASH), “zero-power” standby modes are often implemented. Zero-power standby modes generally refer to sleep states in which a system or device draws a minimal amount of current and thereby consumes a minimal amount of power. Though typical zero-power standby modes consume relatively less power than normal modes of operation, the standby mode may not truly be a zero-power standby mode, despite the use of the term “zero-power.” Standby modes typically result in a leakage current of 10-20 μA. The leakage current is typically produced from the complimentary metal-oxide-semiconductor (CMOS) technology which is typically used to manufacture SRAM and DRAM devices. CMOS junction leakage, sub-threshold leakage, and gate induced drain leakage (GIDL) in the memory core device. Other CMOS-based devices such as universal serial bus (JSB) controllers, digital signal processors (DSP), and baseband processors may also exhibit these leakage mechanisms. While this amount of leakage current is tolerable in many applications, it would be advantageous to reduce the leakage current to provide a true zero-power standby mode and thus, increase the battery life of the handheld devices.
The present invention may address one or more of the problems set forth above.